A typical label applicator applies one or more labels to an article as the article is conveyed past the label applicator. For example, a label applicator may include a label dispenser which dispenses a label onto a label receiver or applicator section. The applicator section then transfers the label to the article, and this is often accomplished by a blast of gas, typically air, under pressure.
The label is releasably retained on a label receiving surface of the applicator section by vacuum pressure. The blast of gas under pressure must be sufficiently forceful to overcome the vacuum pressure tending to retain the label against the label receiving surface. To assure that the label undergoes relatively stable flight from the label receiving surface to the article, it is also important that the blast of gas under pressure have a shape, i.e. a cross section, which is compatible with the shape of the label being applied to the article.
In the past, various techniques have been used to tailor the shape of the gas under pressure acting to blow the label from the label receiving surface to the article. One technique involves the repositioning of air tubes to shape the blast of gas. Another technique, which is shown by way of example in French U.S. Pat. No. 3,888,725, utilizes a mask which contains openings, the number and location of which are selected in accordance with the desired gas pattern configuration. A mask is very satisfactory for this purpose; however, it is important to be able to quickly provide a different mask to accommodate a label having a different configuration. Speed is important because whenever a labeling line is required to apply a label having a different shape, the entire line must be shut down while the label applicator is appropriately adjusted to accommodate the shape of the new label. The mask of the label applicator of the French patent can be quickly changed; however, a new mask for each new label cannot be created as quickly as desired.
In order to have stable label flight from the label receiving surface of the applicator section to the article, it is also important that the force applied to the label by the gas under pressure be substantially the same at each location on the label where the gas under pressure acts. The French patent discloses an air diffuser which is said to distribute the air under pressure to all portions of the openings so that no portion of the openings is starved for air. However, the system disclosed in the French patent is not believed able to achieve the desired evenness of forces acting on the label.